Role of Tuberin in Cell Size and Mitotic Progression

马铃薯蛋白在细胞大小和有丝分裂进展中的作用

• 批准号: RGPIN-2022-04144
• 负责人: Porter, Lisa
• 金额: $ 3.5万
• 依托单位: University of Windsor
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=744811
• 关键词: Role; Tuberin; Cell; Size; Mitotic

A great deal of ground breaking work has determined that the Tuberin and Hamartin complex function as a negative regulator of protein synthesis and cell cycle progression through G1/S. This is largely attributed to the GTPase activity of Tuberin functioning to indirectly inhibit the mammalian target of rapamycin (mTOR). While current work on this pathway is focused on the regulation of G1/S, there is significant evidence which points to a potential role for the Tuberin-Hamartin complex in G2/M regulation. Data from our NSERC program has characterized a direct interaction between Tuberin and the mitotic cyclin, Cyclin B1. We have mapped the Cyclin B1 binding sites in Tuberin and have shown that functionally this interaction delays the shuttling of Cyclin B1 to the nucleus, and subsequent mitotic onset. Interestingly, we have demonstrated that in the absence of nutrients, and/or Akt phosphorylation of Tuberin, the Tuberin-Cyclin B1 interaction is reduced and cells enter mitosis. This raises the exciting possibility that Tuberin regulates a novel cell cycle checkpoint linking mitotic onset with the nutritional status of the cell. Resolving the molecular mechanism by which Tuberin and Cyclin B1 interact, and the consequences of this on cell cycle regulation and overall cell physiology are the focus of this research program. Hypothesis: A direct interaction between Tuberin and Cyclin B1 constitutes a key component of a novel cell cycle checkpoint whereby initiation of mitosis is linked to the external growth conditions of the cell. This checkpoint functions in part to regulate cell size and differentiation decisions in the presence of specific growth/differentiation factors and nutrients. Overall Objective:  This research program aims to reveal the mechanism(s) of how the TSC regulates cell proliferation and the core cell cycle machinery. Short-Term Objective: Using the plethora of tools we have developed we will: 1.Dissect the dynamics of Tuberin interactions with CycB1 in response to environmental stressors. 2.Resolve the components of the Tuberin-CycB1 complex in early G2 vs at the onset of mitosis. 3.Study Tuberin-CycB1 interactions in vivo and in vitro during cell fate decisions. Long-Term Objective: We will move our tools to study Tuberin interactions with Cyclin B1 into mouse and zebrafish models to determine the in vivo consequence of this checkpoint on development, maintenance and response to stress.   Our data has revealed a novel and exciting regulatory mechanism controlling the onset of mitosis. This research program seeks to resolve the molecular complexities and the cellular consequences of this interaction; data which is essential for understanding normal cell growth mechanisms.

大量开创性的工作已经确定，结核菌素和Hamartin复合物作为蛋白质合成和细胞周期G1/S进程的负调节剂发挥作用。这在很大程度上归因于具有间接抑制雷帕霉素哺乳动物靶标（mTOR）功能的雷帕霉素的GTclase活性。虽然目前对这一途径的研究主要集中在G1/S的调控上，但有重要证据表明，在G2/M调控中，β-胡萝卜素-Hamartin复合物具有潜在的作用。来自我们的NSERC计划的数据已经表征了细胞周期蛋白和有丝分裂细胞周期蛋白，细胞周期蛋白B1之间的直接相互作用。我们已经绘制了细胞周期蛋白B1的结合位点，并已表明，在功能上，这种相互作用延迟穿梭细胞周期蛋白B1的细胞核，随后有丝分裂的开始。有趣的是，我们已经证明，在缺乏营养和/或Akt磷酸化的细胞周期蛋白，细胞周期蛋白B1的相互作用减少，细胞进入有丝分裂。这提出了一个令人兴奋的可能性，即Escherin调节一种新的细胞周期检查点，将有丝分裂的开始与细胞的营养状态联系起来。解决的分子机制，通过它和细胞周期蛋白B1相互作用，以及这对细胞周期调控和整体细胞生理学的后果是这个研究计划的重点。 假设：细胞周期蛋白B1和细胞周期蛋白B1之间的直接相互作用构成了一个新的细胞周期检查点的关键组成部分，有丝分裂的启动与细胞的外部生长条件有关。在特定生长/分化因子和营养物的存在下，该检查点部分地起到调节细胞大小和分化决定的作用。 总体目标：本研究计划旨在揭示TSC如何调节细胞增殖和核心细胞周期机制的机制。 短期目标：使用过多的工具，我们已经开发，我们将：1.解剖的动态的cycB 1的相互作用，以应对环境压力。 2.在G2早期与有丝分裂开始时解决B-CycB 1复合物的组分。 3.研究在细胞命运决定过程中，体内和体外的Escherichin-CycB 1相互作用。长期目标：我们将把我们的工具转移到小鼠和斑马鱼模型中，研究细胞周期蛋白B1与细胞周期蛋白B1的相互作用，以确定这个检查点对发育、维持和应激反应的体内后果。 我们的数据揭示了一个新的和令人兴奋的调控机制控制有丝分裂的开始。该研究计划旨在解决这种相互作用的分子复杂性和细胞后果;数据对于理解正常细胞生长机制至关重要。